This invention relates to a mechanical seal for a rotatable shaft which is substantially free of forces in an axial direction of the shaft, and more particularly to such a mechanical seal located in a mechanically-live bore or bushing or the like wherein the seal includes two groups of discs arranged in axial spaced-apart and generally face-to-face relationships to mesh with one another in the manner of a labyrinth, one group of discs is disposed on the rotatable shaft; while the other group of discs is disposed in a nonrotatable manner in a bore of a bushing extending centrally around the shaft.
A labyrinthine seal for a rotatable shaft is generally well known in the art. Such a seal is constructed in a manner generally similar to the mechanical seal described hereinbefore and is classified in the category of a contactless seal.
West German Pat. No. 2,647,016 discloses a sliding ring-type seal disposed in a casing wherein a relatively low average flow of a pressurized medium acts on one side of the seal and a relatively high average flow of a pressurized medium acts on the other side. The sliding ring seal extends around a shaft that rotates in the bore of a casing. This kind of seal comprises relative rotatable sliding rings or slip rings, that is, one ring is secured to the casing and another ring is secured to the shaft. The two rings have contacting seal surfaces, one of which is larger than the other. The larger seal surface is acted upon by the average flow pressure of the medium in a non-contacting region. A pressure difference of the medium is produced by the flow of the medium which distorts the larger surface of the ring and permits a leakage flow of the medium between the contacting surfaces.